如何使用Kivy中的按钮在另一个屏幕中创建标签

from kivy.app import App
from kivy.uix.button import Button
from kivy.uix.label import Label
from kivy.uix.screenmanager import ScreenManager, Screen

class MyScreenManager(ScreenManager):
    pass

class Screen1(Screen):
    pass

class Screen2(Screen):
    pass

class Screen1(Screen):
    def __init__(self, **kwargs):
        super(Screen1, self).__init__(**kwargs)
        button = Button(text='切换到Screen2', on_release=self.switch_screen)
        self.add_widget(button)

    def switch_screen(self, *args):
        self.manager.current = 'screen2'

class Screen2(Screen):
    def __init__(self, **kwargs):
        super(Screen2, self).__init__(**kwargs)
        label = Label(text='这是一个标签')
        self.add_widget(label)

class MyApp(App):
    def build(self):
        screen_manager = MyScreenManager()
        screen_manager.add_widget(Screen1(name='screen1'))
        screen_manager.add_widget(Screen2(name='screen2'))
        return screen_manager

if __name__ == '__main__':
    MyApp().run()